Oscillatory circuit



Nov. 6, 1934. c w HANSELL 1,980,158

OSCILLATORY CIRCUIT Original Filed May 1, 1931 2 Sheets-Sheet 2 I l I oINVENTOR CLARENCE W. HANSELL ATTORN EY Patented Nov. 6, 1934 UNITEDSTATES PATENT OFFICE N. Y., assignor to Radio Corporation of America, acorporation of Delaware Original application May 1, 1931, Serial No.534,255. Divided and this application June 6. 1932, Serial No. 615,643

17 Claims.

This case is a division of my copending application, Serial Number534,255, filed May 1, 1931, entitled oscillatory circuits and in generalrelates to apparatus for generating high frequency undulatory electricalcurrents. In particular it relates to new and useful circuits employingelectron discharge devices for generating high frequency oscillations,and resonant transmission line means for frequency controlling thefrequency of oscillations generated by the devices.

In my copending application, Serial Number 400,489, filed in the UnitedStates Patent Office October 18, 1929, I have described a systememploying resonant transmission line frequency control whereby, by theuse of a transmission line, long, relative to the working wave lengthcoupled to an oscillation generator, the frequency of oscillationsgenerated by the generator is maintained constant and depends upon theline employed. 29 The frequency controlling action of the line may beattributed to the fact that the line has the effect of a sharply tunedresonant circuit whose reactance changes rapidly with change offrequency and which change of reactance is utilized to keep thefrequency of an oscillator relatively constant. Since the resonantfrequency of the line and the circulating current in it are determinedchiefly by the length of the line, and since the line length issubstantially constant, a high degree of frequency stability isobtained.

Another way of looking at this action is to consider the fact that in aresonant transmission line there will be present on the line an ingoingwave and a reflected wave. At the electron discharge quency, there willbe a decided shift in phase between the ingoing and reflected waves,brought about by the waves traveling and returning along the line. Thatis to say, for a slight shift in frequency, there will be a shift inphase between the ingoing and reflected waves at the input end of theline directly proportional to the number of half wave lengths containedin the line. By making the line very long, the shift in phase for asmall shift in frequency will be very large, as a result of which theelectron discharge device oscillator will be rapidly forced back intooscillation at a desired frequency for which the phase shift between theingoing and reflected wave is zero.

I have attempted to basically cover the foregoing system of frequencycontrol in my copending application Serial Number 400,489. The principalobject of my present invention is to provide improved circuits utilizingresonant transmission lines for frequency control.

device end of the line, with a slight shift in fre- Other objects aswell as advantages of my present invention will become apparent as thedescription thereof, which will be given with the aid of theaccompanying drawings, proceeds.

In the drawings;

Figure 1 illustrates a pushpull resonant long line frequency controlledregenerative oscillation generator wherein negative bias on the controlelectrodes of the devices forming the generator is imparted through aconnection made at a point of substantially zero radio frequencypotential on the long line frequency controlling arrangement;

Figures 1a and 1b are modifications of the arrangement illustrated inFigure 1 and in particular illustrate the use of concentric resonanttransmission lines for frequency control;

Figure 2 is a similar arrangement wherein the long line couples outputand input circuits of a pushpull oscillation generator, an additionalhalf wave length circuit being provided to start and maintainoscillations at extremely high frequencies; and,

Figure 3 illustrates a system somewhat similar to Figure 2 wherein longlines of different lengths are connected to the control electrodes andanodes of a pushpull electron discharge device oscillation generator.

Figure 1 illustrates a long line frequency controlled regenerativeoscillator which has been used with considerable success in actualpractice. Electron discharge devices 48, 50 which may be either the aircooled or liquid cooled type have a resonant long line 6 coupled to theinput electrodes 49, 51 thereof and a tunable output circuit 52connected across their anodes 53, 55. Through the action of resistor 54connected between the cathodes 57, 59 and the grids 51, 53 and connectedto the variable slider 56 for altering the length of the line, the grids51, 53 of the tubes 48, 50 are maintained at a suitable operatingpotential or negative bias with respect to the cathodes. By adjustmentof neutralizing condensers 58, the amount of feed back may be controlledat will. If desired, these neutralizing condensers may be omitted andthe regeneration adjusted by varying the length of the line 6 and thetuning of circuit 52 by such relative amounts as to keep the frequencyfixed. As illustrated, the output circuit 52 includes a lumped inductorand a lumped variable capacitor, and the plates are maintained at apositive potential with respect to the cathodes.

Modulation may be accomplished by varying the current fiow through themodulating tubes 60 whereby the current flow through the oscillators 48,50, is varied inasmuch as the current cuit 52 may be directly radiated,or, may be further amplified andfrequenoy multiplied by the use ofadditional amplifier 64 and thence radiated over a suitableantenna 66;Preferably, the antenna should be directive.

In order to check the frequency of oscillations of the system shown inFigure 1, the radio frequency'amplifier 68 may be coupled to anyoscillating portion of the system so that its output feeds a detector'70 alsosupplied with energy of known frequency from, say a crystalcontrolled harmonic generator 72. The frequency of the beat resultingfrom the two sources of energy may then be indicated in a suitableindicating device 74, and, by adjustment of slider 56, so that the beatbecomes of a desired value, the transmitter may be adjusted to any.suitable or desirable operating frequency. Obviously, the frequencychecking and monitoring device may also be used with any of the otheroscillators described.

Of course, changes may be made to the arrangement shown in Figure 1.Thus, as shown in Figures 1a and lb a parallel tuned input circuit 61 isconnected across the grids 49, 51 and the resistor 54 connected from amid-point of the tunable input circuit to the cathodes for maintainingcorrect bias. Moreover, this mid-point connection may be grounded by theuse of a condenser 63 for radio frequency potentials. The long resonantline may then be conductively coupled to the tunable input circuit asshown in Figure la or inductively coupled to the input circuit as shownin Figure 1b.

Moreover, the long line, shown in Figures 1a and 1b may be made ofconcentric conductors 65, 67, variable adjustment being accomplished bythe use of a disk 69 or other suitable device within the outer conductorcontacting with both the outer and the inner conductor and beingslidable within and along the outer conductor 65.

In the arrangementshown in Figure 2, a long resonant transmission line 6couples the output electrodes of electron discharge devices 48, 50 tothe tunable input circuit thereof. The long line 6 in this case actsboth as a resonant output circuit as well as a frequency controllingmedium. The input circuit 80 is preferably in the form of a coil orlooped conductor substantially one-half wave length long, the wavelength taken being that of a desired operating frequency. The anodepotential may be supplied through radio frequency choke 82 and lead 84upon which signal voltages are impressed through the action of atransformer 86. Output energy may be taken through blocking condensers88 to transmission line 90 and utilized as desired.

Figure 3 illustrates an oscillator which has been found useful forproducing very high radio frequencies. A long resonant line 6 is coupledto the grid electrodes of electron discharge devices 48, 50 and anotherlong resonant line '1 pref erably of a length different from 6, iscoupledto the output electrodes thereof. In this manner several standingwaves on the grid and anodeleads at resonance are obtained at thedesired frequency. Anode potential as well as modulating potentials aresupplied through a lead 84 and fed to the anodes through the longresonant line 7. Output energy may be taken from the resonant linethrough transmission line 90 and radiated from a suitable antenna orradiator 92.

In order to start and maintain oscillations at the frequency higher thanthe lowest frequen y 1,9so,1as

for which the circuits are resonant, a circuit suchas circuit 94 iscoupled to the oscillators 48, 50. This circuit has a low power factorand a minimum resonant frequency equivalent to the frequency desired.For a suitably designed circuit and proper coupling to the oscillators,the system will operate at the frequency desired. (Justomarily thecircuit 94 takes theform of a U-shaped pieceof copper a half wave lengthlong at the desired oscillation frequency and is coupled capacitively asshown to the oscillators 48, 50. The circuit 94, as shown, is closelycoupled to the system through the blocking condensers 95 whichact-substantially as short circuits for the high frequency currents.

Having thus described my invention, what I claim is:

1. A regenerative oscillation generating system comprising a pair ofelectron discharge devices each having an anode, a cathode and a controlelectrode, analternating current circuit connected across said anodes,means for connecting said cathodes together. a circuit comprising a pairof transversely spaced rectilinear conductors parallel to each other andhaving uniformly distributed inductance and capacity, each ofsaidconductors being more than one-half wave length long at the desiredoperating frequency connected to said control electrodes, and, aresistance connected between a voltage nodal point on said lastmentioned rectilinear conductor circuit, and

said cathodes.

2. A regenerative oscillation generating system comprising a pair ofelectron discharge devices each having an anode, a cathode and a controlelectrode, an alternating current circuit connected across said anodes,a source of potential connected between said anodes and cathodes, a twoconductor transmission line, long, relative to a desired operating wavelength, operatively con nected to the control electrodes of saiddevices, a simple conductor connected across said transmission line topoints on said line electrically remote from said control electrodes,means for subjecting saidcontrol electrodes to a suitable negativebiasing potential connected between an intermediate point on said simpleconductor and said cathodes, and a load coupled to said alternatingcurrent circuit.

3. A regenerative oscillation generator comprising a pair of electrondischarge devices each having an anode, a cathode and a controlelectrode, an alternating current circuit connected across said anodes,a condenser connecting the anode of one of said devices to the controlelectrode of another, another condenser connecting the anode of saidother device to the control electrode of one device, said condensersbeing adjusted to establish regeneration, between said anode circuit andsaid control electrodes, of a value to establish continuous oscillationgeneration, and frequency controlling means coupled to controlelectrodes of said devices, said frequency controlling means comprisinga pair of rectilinear conductors having uniformly distributed inductanceand capacity.

4. A regenerative system for generating high condensers, cross-connectedbetween the anodes and control electrodes of said devices adjusted toestablish feed back from said anode circuit to said control electrodecircuit of a value to establish and maintain oscillations.

5. In a system for regeneratively generating high frequencyoscillations, a pair of pushpull connected electron discharge deviceseach having an anode, a cathode, and a control electrode, a resonantcircuit including a lumped inductor coupled to said anodes, and aresonant transmission line comprising a pair of rectilinear conductorshaving uniformly distributed inductance and capacity operatively coupledto said control electrodes, means for varying the length of said line, aresistance connected between said length varying means and said cathodesfor maintaining the control electrodes to which said line is coupled ata suitable operating potential, and means connected between the anodesand cathodes for subjecting the anodes to an operating unidirectionalpotential.

6. A regenerative oscillation generator comprising a pair-of electrondischarge devices each having an anode, a cathode and a controlelectrode, a circuit substantially one-half wave length long at adesired operating frequency operatively coupled to electrodes of saiddevices for starting and maintaining high frequency oscillations, aresonant transmission line, long relative to the wave length ofoscillations generated by said de vices, coupled to electrodes of saiddevices for stabilizing the frequency of oscillations generated thereby,and circuits connected between the control electrodes and cathode andbetween the anodes and cathodes for subjecting said control electrodesto negative potentials and said anodes to positive operating potentialswith respect to said cathodes.

7. A regenerative system for generating high frequency oscillationscomprising a pair of electron discharge devices each having an anode, acathode and a control electrode, a circuit having substantiallyuniformly distributed inductance and capacity substantially one-halfwave length long at a desired operating frequency capacitively connectedto the control electrodes of said devices, and, another circuit,comprising a pair of transversely spaced parallel rectilinear conductorshaving substantially uniformly distributed inductance and capacityseveral half wave lengths long at the desired operating frequencyoperatively connected to the control electrodes ofsaid devices, forstabilizing and frequency controlling the frequency of oscillationsgenerated by said devices.

8. In apparatus of the character described, a pair of electron dischargedevices each having an anode, a cathode and a control electrode, acircuit, having substantially uniformly distributed inductance andcapacity and electrically one-half wave length long at the desiredoperating frequency, connected across said control electrodes, and, apair of substantially rectilinear conductors having substantiallyuniformly distributed inductance and capacity and several half wavelengths at adesired operating frequency, coupling said anodes to saidcontrol electrodes.

9. A system for the regenerative generation of high frequencyoscillations comprising a pair of electron discharge devices each havingan anode, a cathode and a control electrode, a circuit comprising aconductor having a single loop therein and having substantiallyuniformly distributed inductance and capacity and substantially onehalf,wave length long at a desired operating frequencyfcapacitively coupledin phase opposition to said control electrodesi iiotheiemircuilcomprising a pair of transversely spaced subsiFaritiallr-EF y} parallelsubstantially rectilinear conductors having substantially uniformlydistributed inductance and capacity, but many wave lengths long at adesired operating frequency connected to said control electrodes, and athird circuit comprising a pair of substantially parallel substantiallyrectilinear conductors having substantially uniformly distributedinductance and capacity and many wave lengths long at a desiredoperating frequency connected across the anodes of said electrondischarge devices.

10. In a system for regeneratively generating high frequencyoscillations, a pair of pushpull connected electron discharge deviceseach having an anode, a cathode and a control electrode, a resonantcircuit coupled to said anodes, a resonant transmission line comprisinga*pair of rectilinear transversely spaced substantially parallelconductors having uniformly distributed inductance and capacityconnected to said control electrodes, a connection connecting theconductors together at points on said conductors electrically remotefrom said control electrodes, said connection having low resistance todirect currents, a biasing circuit connected between said connection andsaid cathodes for suitably biasing said 105 control electrodes withrespect to said cathodes,

and, a circuit connected between said anodes and cathodes for subjectingsaid anodes to suitable operating potentials.

11. An oscillation generator comprising a pair of electron dischargedevices each having an anode, a cathode and a control electrode, analternating current circuit connected across said anodes, condenserscross-connecting the anodes and control electrodes of said devices, saidcondensers being adjusted to establish regeneration of a value such thatcontinuous oscillations are generated, a rectilinear conductor connectedto the control grid of one of said devices, said conductor havingsubstantially uniformly distributed inductance and capacity, asubstantially similar conductor connected to the control electrode ofthe other device, said conductors being arranged so as to betransversely spaced and be parallel with respect to each other, aneffective direct current short circuit connection connected across saidconductors, and a biasing circuit connected between said shortcircuiting connection and said cathodes for subjecting said controlelectrodes to a suitable operating potential.

12. A constant frequency regenerative oscillation generator comprising apair of multi-electrode devices each having an anode, a cathode and agrid, meansconnecting the cathodes together, a tuned high frequencycircuit connected between the grids, a high frequency circuit coupled tothe anodes, means for subjecting said control grids and anodes topotentials such that oscillations are generated by said devices, and, apair of substantially straight conductors arranged parallel to oneanother and arranged so as to have standing waves thereon, coupled tosaid tuned grid circuit for stabilizing the frequency of oscillationsgenerated by said devices.

13. A regenerative oscillation generating sys- 1 tern comprising a pairof devices each having an anode, a cathode and a grid, means connectingthe cathodes together, a resonant circuit connected between said grids,a resonant circuit connected to said anodes whereby oscillations aregenerated by said devices and flow in said circuits associated with saidgrids and anodes, and, a pair of substantially linear conductors coupledto the tuned circuit connected between said grids, said linearconductors being 4 arranged substantially parallel to each other andbeing spaced from.each other in such a way as to prevent radiation ofenergy therefrom.

14. A constant frequency oscillation generator comprising a pair ofmultl-electrode devices each having an anode,'a cathode and a grid,means connecting the cathodes together, a tuned high frequency circuitconnected between the grids, a high frequency circuit connected to theanodes, means for subjecting said control grids and anodes to potentialssuch that oscillations are generated by said devices, and a pair ofsubed to have standing waves produced thereon, coupled to said tunedhigh frequency circuit connected to said grids for stabilizing thefrequency of oscillations generated by said devices.

15. A constant frequency oscillation generator comprising a pair ofmulti-electrode devices each having an anode, a cathode and a grid,means connecting the cathodes together, a tuned high frequency circuitconnected between the grids, a high frequency circuit connected to theanodes, means ---for. subjecting said control grids and anodes topotentials such that oscillations are generated by said devices, and apair of sub-- stantially straight concentric conductors adapted to' havestanding waves produced thereon, inductively coupled to said tuned highfrequency circuit connected to said grids for stabilizing the frequencyof oscillations generated by said devices.

16. A constant frequency regenerative oscillation generator comprising apair of multi-electrode devices each having an anode, a cathode and agrid, means connecting the'cathodes together, a'tuned high frequencycircuit connected to the grids, said tuned circuit including a lumpedinductor, another tuned high frequency circuit including a lumpedinductor connected to the anodes of said devices, means for subjectingsaid grids to .a negative potential with respect to said cathodes, meanssubjecting said anodes to a posi- I tive potential with respect to saidcathodes, and a pair of substantially straight concentric conductorsadapted to have standing waves thereon coupled to said tuned gridcircuit for stabilizing the frequency of oscillations generated by saiddevices. stantially straight concentric conductors adaptductors adaptedto have standing waves thereon conductlvely connected to said tuned gridcircuit for stabilizing the frequency of oscillations generated by saiddevices.

CLARENCE W. HANSELL.

